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Finding the Secondary Node

Simplyblock, in high-availability mode, creates two connections per logical volume: a primary and a secondary connection.

The secondary connection will be used in case of issues or failures of the primary storage node which owns the logical volume.

When to Use This

Checking the secondary node is useful when:

  • validating HA placement after cluster changes,
  • investigating failover behavior,
  • troubleshooting node-level performance or availability issues.

Primary vs Secondary Node

In HA mode, logical volume ownership and replication state span primary and secondary storage nodes. The primary node typically serves active ownership, while the secondary node is part of failover readiness and recovery.

Prerequisites

Before running the check:

  • Ensure sbctl is configured and can access the control plane.
  • Ensure the primary storage node ID is known.
  • Ensure cluster and storage-node state is reachable.

Find the Secondary Node ID

For debugging purposes, find which host is used as secondary for a specific primary storage node by querying storage-node details and filtering for the secondary field:

Find secondary for a primary
sbctl storage-node get <NODE_ID> | grep secondary_node_id

Interpret the Output

  • If secondary_node_id is present and populated, that value is the paired secondary node.
  • If the field is missing or empty, possible reasons include:
  • non-HA configuration,
  • transitional state during migration/rebalancing,
  • unavailable metadata due to API or cluster issues.

Validate the Secondary Node

After obtaining the secondary node ID, verify that node is healthy:

Inspect the secondary node
sbctl storage-node get <SECONDARY_NODE_ID>
List storage nodes for status cross-check
sbctl storage-node list --cluster-id=<CLUSTER_ID>

Troubleshooting

  • If no secondary is reported, verify the affected logical volumes are configured for HA.
  • If the secondary node appears offline or degraded, investigate node health and recent events first.
  • If values appear stale, re-run the query after short intervals while checking cluster health.